It doesn't necessarily require a Ph.D in advanced mathematics to be an NBA coach in 2012.

But when the Spurs' staff of paid number-crunchers presents Gregg Popovich with the daily statistical updates on the state of his team, it can certainly feel that way.

“It's almost like integral calculus,” Popovich said.

Yet the numbers often confirm what Popovich's old-school eye has been telling him over the first two months of the season.

“We're significantly better on defense than we were the last couple of years,” Popovich said. “That's something we hope will continue as the season progresses, and not just be a blip.”

In the olden days of a couple years ago, Popovich's favored stat for determining defensive fortitude was field-goal percentage defense.

It has been three seasons since the Spurs finished among the NBA's top 10 in that category. More than a quarter of the way through this season, they are tied for eighth, yielding 43.7 percent to opponents.

Using new math preferred by stat heads across hoopsdom — points allowed per 100 possessions — the Spurs' rating of 101.8 ranks fourth in the league.

“Everybody's making a conscious effort to do better on the defensive end,” point guard Tony Parker said. “We're understanding what Pop wants and make sure we do it consistently.”

The Spurs' rediscovered defensive mettle will be tested tonight, when they conclude a four-game homestand against a blistering Houston team suddenly scoring at will.

Before Wednesday's 87-84 victory at Minnesota, the Rockets had notched at least 120 points in three straight games, winning all three by no less than 22.

Houston arrives on a five-game winning streak, and with a scoring average of 104.8 points that ranks second in the NBA, just ahead of the Spurs (104.4).

The Rockets' catalyst has been guard James Harden, the NBA's fourth-leading scorer heading into Thursday's schedule at 25.8 points per game.

“They've got some momentum right now, playing great basketball,” Parker said. “They're a great test for us.”

In terms of raw scoring defense, the Spurs are allowing 97 points per game, 15th in the league.

But that number is close to meaningless.

Modern NBA numbers geeks favor the more sophisticated defensive efficiency models because they account for pace. Teams that play faster on offense will have to defend more possessions on the other end, naturally inflating raw points-per-game statistics.

The numbers that matter agree the Spurs are playing all-around better defense than they were last season, when they finished 10th in defensive rating.

Explaining that improvement, given the Spurs' lack of turnover from last year to this year, is a task best left to humans.

Lately, the Spurs have settled into what should be their best defensive starting lineup. In guard Danny Green and small forward Kawhi Leonard, the Spurs boast one of the top combinations of wing defenders in the league.